Support string constexpr kernel args; scope googletest to examples

[tengqm]

Two independent fixes surfaced while building FlagGems' C++ operators against this library on the Enflame (GCU) backend.

1. String constexpr arguments failed to compile

ArgHandle::handle_arg_plain() routes every non-Tensor / non-nullopt argument through a runtime branch whose handlers (handle_specialized, handle_specialized_no_alignment, handle_non_constexpr) all evaluate triton_type<T>::name. For a string argument — e.g. a dtype spelled "tl.float32", passed by FlagGems' GCU mm kernel — triton_type has no specialization, so the template failed to instantiate:

error: 'name' is not a member of 'triton_jit::triton_type<const char*>'

even though a string argument is always a constexpr Triton parameter at runtime. The CUDA path never passed a string, so it compiled.

Fix: add a compile-time else if constexpr for const char* / char* / std::string / std::string_view that routes strings straight to handle_constexpr, mirroring the existing nullopt handling, so the specialized / non-constexpr paths are never instantiated for a string type.

2. googletest fetched unconditionally

add_subdirectory(src) precedes the googletest fetch, so the library itself never needs gtest — only the examples do. But the FetchContent(googletest) sat outside the TRITON_JIT_BUILD_EXAMPLES guard, so every subdirectory consumer (e.g. FlagGems via FetchContent) downloaded googletest anyway.

Fix: move the googletest fetch inside the TRITON_JIT_BUILD_EXAMPLES block.

Verification

FlagGems' flag-gems-cpp-gcu extension now builds against this library with no string-arg compile error and no googletest download.

🤖 Generated with Claude Code